How to Choose the Right Charger for iPhone & Samsung Phones (and Protect Battery Health)

Buying a modern flagship smartphone like an iPhone or a Samsung Galaxy comes with one immediate surprise: there is no wall charger in the box.

While this shift reduces electronic waste, it leaves millions of users with a confusing choice. Should you grab a cheap 20W brick from an impulse display, reuse a 5W power adapter from 2018, or buy a high-wattage 65W laptop charger?

Choosing the wrong charger can lead to excessive thermal throttling, slower charging speeds, or accelerated lithium-ion degradation. Here is your comprehensive guide to selecting the perfect charger for iPhone and Samsung devices while keeping your battery healthy for years.

1. Understand Key Protocols: USB-PD vs. PPS

Not all fast charging is created equal. Modern iPhones and Samsung phones rely on open-standard power protocols to regulate voltage and current safely.

USB Power Delivery (USB-PD) for iPhone

Apple uses USB Power Delivery (USB-PD) across its entire lineup. USB-PD dynamically negotiates output between the wall adapter and the phone to deliver optimum power safely.

• Minimum Requirement: USB-PD fast charging requires a 20W to 30W USB-C charger.

• Compatibility: Works on iPhone 8 up to the latest iPhone models.

Programmable Power Supply (PPS) for Samsung

Samsung uses an advanced subset of USB-PD called PPS (Programmable Power Supply). PPS allows the charger to make micro-adjustments to voltage and current every 10 seconds based on the phone’s temperature and charge level.

• Standard Fast Charging: Requires a 25W USB-PD 3.0 (PPS) charger.

• Super Fast Charging 2.0: Requires a 45W USB-PD 3.0 (PPS) charger paired with a 5A-rated USB-C cable.

⚠️ Key Takeaway: If you plug a Samsung Galaxy into a standard 45W charger without PPS support, the phone will default to slow 15W charging to protect itself from heat.

2. Match the Wattage (Without Worrying About Overcharging)

A common myth is that plugging a 20W iPhone into a 65W MacBook charger will “fry” the battery.

Smartphones control how much power they draw—not the charger. A 65W GaN (Gallium Nitride) wall charger will safely deliver only the maximum wattage your iPhone or Samsung model requests.

Recommended Wattage Matrix:

3. The Role of Heat in Battery Health

Lithium-ion batteries chemically degrade due to two main enemies: extreme heat and voltage stress. High temperatures cause internal resistance to build up, shortening maximum battery capacity over time.

How Proper Chargers Reduce Heat:

1. GaN (Gallium Nitride) Technology: Modern GaN chargers operate far more efficiently than older silicon-based chargers, generating significantly less waste heat at high outputs.

2. Stepped Charging Curves: Certified chargers deliver full power from 0% to 50%, then automatically ramp down power as the battery reaches 80% to avoid overheating the cell.

4. Software Rules to Extend Battery Longevity

Matching the hardware charger is only half the battle. Both Apple and Samsung provide built-in battery preservation tools inside their OS settings:

iPhone Battery Health Settings:

• 80% Charge Limit: Available on iPhone 15 and newer models under Settings > Battery > Charging. This prevents the chemical degradation associated with holding a full 100% charge overnight.

• Optimized Battery Charging: Uses machine learning to hold charging at 80% overnight, finishing the last 20% right before your regular alarm rings.

Samsung Galaxy Battery Care:

• Protect Battery / Battery Protection: Found under Settings > Battery > Battery Protection. Choose Basic, Adaptive, or Maximum (which caps charging at 80% or 85%) to reduce cycle wear.

Checklist: What to Look for Before Buying a Charger

Before buying a new wall brick or wireless pad, verify the following details:

• USB-C Output: Look for a USB-C port rather than older USB-A ports.

• USB-PD 3.0 & PPS Support: Ensures full compatibility for both Apple and Samsung devices.

• Safety Certifications: Check for UL, CE, FCC, or MFi (Made for iPhone) certification logos.

• Quality Cable: A 45W Samsung charger requires a 100W / 5A e-Marked USB-C cable to hit peak charging speeds.